Experts had thought the a reversal in the steady decline in self-reported racial prejudice up until 2001 would be impossible.

However concerns over immigration, and the impact of the terror attacks in New York, are likely to have fuelled the long term rise, experts said.

The survey’s findings come as the Uk Independence Party, which launched a hard hitting poster and broadcast campaign against high levels of immigration to Britain, swept the European election and saw a surge in support at a local level.

Penny Young, the chief executive of NatCen Social Research, said the "marked turning around" in the figures after 2001 suggested the change could be linked to the impact of the terrorist attacks in September 2001 in the US. Fears over immigration were another likely contributing factor, she said.

Speaking on Radio 4’s Today programme, she said: "Back in 1983, when we started British Social Attitudes, it looked as if it was an inexorable decline, it looked like as if it was part of increasing socially liberal Britain, so things like attitudes towards same-sex marriage, having children before marriage and so on, they were all going in one direction.

"On this trend, in about 2001, it seemed to change, and we think there are probably two possible things that are driving this. One, it was a very marked turning round in 2001, so it may well be an impact of 9/11, that people started to feel more fearful, or to do with people feeling concerned about the impact of immigration in their own area or being fearful of the impact of immigration in their own area."

London, home to a high proportion of immigrants, was the least racially prejudiced area in the UK with 16 per cent of people reporting that they were prejudiced on the basis of race. The most racially prejudiced area was the West Midlands at 35 per cent.

Levels of prejudice rose with age with 25 per cent of 17 to 34 year old describing themselves as racially prejudiced in comparison to 36 per cent of over 55s.

More educated people were half as likely to report racially prejudiced view with 19 per cent of those with a degree reporting racial prejudice compared to 38 per cent of those with no qualifications.

Just over nine in 10 of those who admitted to some level of racial prejudice said they would also like to see a reduction in immigration levels, compared with around seven in 10 who said that were not prejudiced at all.

Sadiq Khan, the shadow justice minister, said that findings were “clear evidence” that politicians should not be complacent about prejudice that “blights” society.

Trevor Philips, the former chair of the Commission for Racial Equality and Human Rights, said: “Integration does not just happen by accident: You have to work at it.

“If we want to avoid a slow descent into mutual bigotry we need to drop the dogma, weigh the evidence without sentiment, recognise the reality and work out a programme – both symbolic and practical – to change the reality."